Patent GB-593284-A (GB)
Title: Improvements in or relating to the production of protein fibres, filaments, yarns and threads
IPC: D01F4/00
Filed: 1945-06-08
Abstract: Soybean protein artificial filaments, fibres, yarns and threads of improved tenacity and elasticity are obtained by extruding an aqueous alkaline soybean protein spinning solution containing from 13 to 15 per cent by weight of soybean protein and from 1.0 to 1.4 per cent by weight of an alkaline reacting compound having a basic dissociation constant greater than 1 x 10-5 into an acid aqueous coagulating bath containing from 0.01 to 1 per cent by weight of a cation-active surface-active agent.  Specified alkaline reacting compounds are caustic alkalies, ammonia, amines, quaternary ammonium hydroxides and quaternary sulphonium hydroxides.  Suitable cation-active agents are quaternary ammonium, quaternary phosphonium and tertiary sulphonium compounds containing a positively charged ion that contains an aliphatic hydrocarbon group having at least 6 carbon atoms.  The coagulating bath, in addition to the cation-active agent, also preferably contains at least 0.1 per cent formaldehyde, from 0.5 to 10 per cent of one or more strong mineral acids such as sulphuric, hydrochloric, nitric and sulphamic acid, and at least 10 per cent of one or more water-soluble inorganic salts such as sodium chloride or the sulphates of sodium potassium, aluminium, magnesium and zinc. The coagulating bath temperature may range from 20 DEG  to 80 DEG  C. The coagulated filaments are stretched at least 50 per cent of their maximum draw ratio in an aqueous salt solution at a temperature above 50 DEG  C., and containing at least 5 per cent of one or more soluble neutral or acid reacting inorganic salts such as the sulphate of sodium aluminium or zinc or the chloride of sodium or potassium, with the addition, if desired, of small amounts of organic acid salts such as sodium acetate and potassium formate.  The stretched materials are hardened in an aqueous formaldehyde bath or baths having a pH of less than 8 and containing at least 5 per cent of one or more inorganic salts. Formaldehyde as such or materials which yield or react like formaldehyde such as paraformaldehyde, trioxymethylene, dimethylol urea and trimethylol nitromethane may be used in the hardening baths. The materials may be further treated with strongly acidified saline-formaldehyde solutions at elevated temperatures by the process described in Specification 513,910. They may also be treated to prevent shrinkage and loss of orientation and may be subjected to neutralizing, softening, blending, sizing and oiling treatments. Before the final hardening step they may be set up by treatment at elevated temperature in a medium which has little swelling action upon them.  In an example, a solution of soybean protein in aqueous sodium hydroxide is extruded into an aqueous coagulating bath at 45 DEG  C. containing sodium sulphate, zinc sulphate, glucose, sulphuric acid, formaldehyde and cetyl pyridinium bromide and the yarn so produced is stretched in an aqueous sodium sulphate solution at 83-88 DEG  C.  The stretched yarn is wound up, moistened with sodium sulphate solution, hardened first in an aqueous bath containing sodium chloride, sodium acetate and formaldehyde and then in an aqueous bath containing sodium chloride, aluminium sulphate and formaldehyde, washed, neutralized with ammonium hydroxide solution and dried.